Glasses



Oct. 12, 1954 Hb H, BLAU 2,691,599

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FIG. 3 A Y# AV C NAVA /NVE/VTOR AVAVAVAV H EN RY H. BLAU Patented Oct.12, 1954 UNITED STATES PATENT OFFICE GLASSES Application November 14,1950, Serial No'. 195,691

19 Claims. 1A

The invention disclosed in this ap-plication relates to new glasseswhich are especially useful for transmission 0I" rays of relatively longwave lengths. Prior hereto'glasses haveusually been formed of fusedsilica orfused mixtures of silica with various other components.Alkalies, alkaline earths', borates and similar materials' are usually'added to glass batches'. I havev found that certain glasses can bemadethat are entirely free of silica and of such other materials. Somesuggestion has` beenk made that glasses shouldbe formed of puregermania. I have discovered that by mixing germaniav and lead oxide,fusing' the components to a liquid' mixture and allowing the mixture tosolidify, I obtaina glass which has qualities of allowing. thetransmission of rays of relatively long wave lengths' in many respectssuperior to any other glasses ofwhich I know and which has higherrefractive indices than most known glasses. The addition of 'cer'- tainother substances in many instances; is also an aid either in securingbetter transmission or in securing stability and resistance to chemicalattack, and. also in improving the viscosity of the glasses. Ihavefound` that puregermania' glass does not have' as good properties inrespect to transmission as the glasses which' I' disclose herein and Ihave found that it is'unstable when exposed to the atmosphere.Germania.` glasses unfortunately have'a much greater tendency todevitrify than' do silicate glasses. I'have also shown by experimentthat pure"germ'ania glasses are not as satisfactory in the above andother respects as the glasses formed of the several components which Ihave disclosed herein.

One of the objects of my invention, therefore, is the production of newglasses.

A further object of my invention is the production of glasses havingunusual optical properties such as relatively high indexes ofrefraction, relatively low dispersion, and relatively high opacity toX-rays and otherlow Wave length radiations.

A further object of my invention is to produce glasses free from or lowin alkalies to which colors can nevertheless be imparted.

A further object'of my invention is the production of glasses havingbetter qualities with regard to transmission of 'rays-"of relativelylong wave length, stability, resistance to chemical and 1 atmosphericattack, etc., than previous glasses of which I am aware.

A further object of my invention is the provision of glasses which allowbetter transmission of much of the infra redrays.

A-further object-of myinvention is the pro# vision o'f glasses, havingrelatively great transmission of infra red rays, which are relativelystable to atmospheric conditions, to abrasion and to chemical attack.

Further objects and features of my invention will be apparent from thesubjoined-specication and claims when considered'in connection with theaccompanying drawings illustrating certain embod-imen'ts o'f' myinvention;

In the drawings:

Fig. l isV a diagram showing:v the limits ofthe usable glass-formingfield of a system ci glasses formedv by lead oxide, lgermania andlanthana;

Fig. 2'is'a similar diagram showing the -limits of the glass-formingfield of aglass systemvin which glasses are formed of lead oxide,germania and-alumina; and

Fig. 3 is asimilar diagram showing the limits of the glass inthe useableglass-forming iield of aglass system in which the -glassesare formed ofthe `compounds of lead oxide',l germania and zirconia.

Referring to the drawings, I- show the 'glasses formed from thecomponents'le'ad' oxide; ger-- mania and lanthanaandhavi'nigl-percentages of the components which may be plotted to lie.

within the' areas A, B and C, are useable. Glasses formed ofpercentagesof compounds plotted to lie Within the area A are stable andhave good transmission of long wave rays. Glasses formed of componentshaving percentages plotted'to lie within the area B are stable glassesbut the transmission of long wave rays is below the average of thetransmission of the glasses formed from percentages of components lyingwithin the area A. Glasses formed of percentages of components plottedto lie within the area C are subject to atmospheric attack but thetransmission of fresh glasses formed from. percentages of the componentsshown is fairly good. In lmy attempts to form glasses having percentagesof components lying within the area D, I found such glassesunsatisfactory inasmuch as they were faulty clue tothe devitriiicationor incomplete' fusion.

Similarly, I found that glasses,A formed of the components germania,lead oxide and alumina lying within the areas A', B, C and D of Fig. 2have' substantially the same characteristics' as the correspondingglasses formed from germania, lead oxide and lanthana which arevdescribed above in connection with Fig. 1. Iny the same way glassesformed of lead'oxide, germania and zirconia -lying within the areas A,B, C and` D of Fig. 3 correpsoncl` substantially to` the corre-Vsponding glasses described above in connection with Fig. l. As shownbelow, I have also discovered the advantages of a PbO-GeOz-AlaOx--Laaossystem. I have also discovered the possibilities of using oxides ofvarious other metals as a third component of a lead oxidegermania glass.Thus, the oxides of the following metals may be used: lithium,beryllium, sodium, magnesium, potassium, calcium, scandium, titanium,vanadium, chromium, manganese, zinc, gallium, rubidium, strontium,yttrium, columbium, cadmium, indium, tin, antimony, cesium, barium,cerium, praseodymium, neodymium, samarium, europium, gadolinium,terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutecium,thallium, bismuth and polonium.

Where it is desired to transmit rays of long Wave lengths, silicon,boron, and phosphorus, even in small amounts should not be tolerated asthe presence of these materials decreases the Wave length transmitted.Lanthana, alumina, zirconia, etc. affect the physical properties of theglass but do not aifect the transmission, except as the transmission isaffected by being able to increase the ratio of lead oxide to germaniumdioxide. The third components mentioned (other than silicon, boron, andphosphorus) affect mainly the working properties of the glass such asviscosity points, handling properties, etc.

In general the ratio corresponding to the most favorable thirdconstituent (other than GeO and PbO) seems to determine the limit forglass formation. Thus the addition of a minor quantity of MnO to alead-germania-lanthana composition seems to permit the glass to beformed substantially as if the MnO were an additional. molecularquantity of La203. The addition of lithia to an alumina glass likewisepermits the glass formation to fall within the alumina ratio. Ifanything, these additions extend the limits of the glass-forming neldsand increase the useable ratios slightly. I believe that MnO isespecially beneficial in this respect.

The limits of the glass-forming field of a system employing thecomponents lead oxide and germania only as established by the weightratio .Phf GeOZ are from to 2.13 (i. e. from 100% germania to 68% Pb()32% GeO2 The limits of the glass-forming field of the components leadoxide, germania, and lanthana as established by the weight ratio PbOGB02 are 0 to 2.6 (i. e. from 100% Ge02 to 72ans GGGQ with Lazos addedin amounts from 0 to 13% (naturally addition of Lagos decreases thetotal percentages of PbO and GeOz). The effect of increasing the ratiosof lead oxide as shown above is to increase the total energy transmittedby transmitting longer wave lengths. However, when the maximum ratio issurpassed, the glass tends to devitrify in batches larger than fivegrams. With good melting techniques, the indications are that the ratiomight be extended slightly. The amount of La203 which may be ratio.

added is seen to reach a maximum of 13% at a ratio of about 1.0 and thendecreases to about 2% at a ratio of 2.6. Greater additions of LazOscaused devitrification. There are indications that small additions ofalkalies may aid in increasing the ratio and consequently the totalenergy transmitted. However, limited quantities of alkalies appear tohave little, if any, effect on the transmission by themselves. In allsystems studied, relatively high ratios of PbO tend to increasetransmission at longer wave lengths and also reduce the cost of theglass where an expensive network former is involved.

The limits of the glass-forming field of a mixture of the componentslead oxide, germania, and alumina, as established by the weight ratioPbO Geog are 0 to 4.65 (i. e. from'l00% GeOz to about with A1203 addedin amounts from O to about 11.5%. The effect of raising the ratio of theadded components is the same as in the system PbO-GeOz-La203- The amountof A1203 which may be added is seen to reach a maximum at a ratio ofabout 1.0 (i. e.

PbO GB02 A darkening of the yellow color of the high PbO glasses towardsa brown may be observed as A1203 is added and replaces GeOa. The effectof limited quantities of alkalies is the saine as in the systemPbO-Ge02-La203.

The limits of the glass-forming field of a system consisting ofPbO--GeOz-ZrOz as established by the weight ratio PbO GB02 are about 0to 4.4 (i. e. from 100% to about 32% rbo Geog with Zr02 added in amountsfrom 0 to 3%). Larger amounts of Zr02 cause either incomplete fusion ordevitrication, depending on the ratio of PbO GB02 PbO Geog in a systemwhere there is no third component is about 2.13% at a ratio of Thelimits of the glass-forming field of a system consisting ofPbO-GeOz-AlzOa--LazOa as established by the weight ratio PbO Geog areabout to 4.45 with the sum of the percentages of A1203 and Lazos varyingfrom 0 to 10%. In general, the percentage of A1203 should either equalor exceed the percentage of LazOa (especially at the higher PbO ratios)to prevent devitrification. The effect of A1203 in this system appearsto be identical with that of A1203 in the system PbO-GeO2-Alz03- Belowthe above is set out in table form:

EXAMPLE I I melted together 65.4% PbO, 30.0% GeOe, 4.0% LazOa, 0.6%M1102. These components were used and allowed to solidify. Glass wasobtained which had good transmission quality in the infrared region, andthe `manganese dioxide racts to prevent or reduce transmission ofvisible wave lengths as well as to stabilize the :glass in the same waythatthe lanthana does.

Limits of the glass-forming field in various systems as established bythe ratio PbO Geog Effect of surpassing This Limit Eifect of IncreasmgLimits of System Lgg Ratio Above Max- Third Commggn'reyd mum Ponent AtLow Ratios At High Ratios PbO-GeO2-Ln2O3 Oto 2.6.... Causes devitriiica-Oto 13% Causes devitr- Causes devitri- Very little effect, if tion inbatches cation. cation. any. Possible delarger than 5 g. colorization.More resistance to abrasion and chemical attack. PbO-GeOZ-Alzo 0 to4.65... Same as above (Im- Oto 11.5%... Increases difii- ..-..do Permitsincreasing proved melting culty-ofiusion. ratio. More resisttechniquemay exance to abrasion tend ratio to and chemical at- 5.00 tack.PbO-GeOr-Zro Oto 4.4-... Same as above (Im- Oto 3% do do Same as inA1203 proved melting system with a postechnique may exsible impairmenttend ratio. of transmission. More resistance to abrasion and chemi icalattack. Pb0-Gc0r-A12O,-La203. Oto 4.45... Same as above Combined 0 do.....do Same as in A1203 to 10%. System.

The process of obtaining these glasses 1s also EXAMPLE II important.Water must be removed from the glass. The process of eliminating waterabsorption bands is quite important and critical. The glass must bemelted in a container free from silica and other harmful substances andthe melt may be carried on in an atmosphere free from moisture. Weprefer however, to dry after melting as disclosed below.

As stated above it is possible to eliminate the water by carrying on themelt in an atmosphere free from moisture. It is more practical howeverto melt without strict precautions as to moisture and to drysubsequently. We usually move the glass after melting and while in amelted condition to a drying furnace which has an atmos phere free ofmoisture. Through this furnace we pass a continuous `stream of dry gas(such as, for example, nitrogen or oxygen) under a slight positivepressure. We may on the other hand allow the glass to solidify afterbeing melted in an ordinary furnace. We may then remelt to purify ofmoisture in a drying furnace. In either event the drying furnaceeliminates the contamination of water. In order to prevent suchcontamination, I melt the glass vor preferably dry it after melting andpossibly after allowing it to harden and remelting in a gas tightfurnace chamber through which a continuous stream of Imelted together70% lead oxide, 29% germania and 1% lanthana. Glass was obtained whichtransmitted about 60% of the rays, at a wave length of 5` microns andapproximately 20% of the rays at a wave length of 6 microns.

EXAMPLE III Imelted together and fused a mixture of 63.0% lead oxide,29.0% germania. 3.0% lanthana and allowed the melt to solidify to form aglass which had similar transmission characteristics.

EXAMPLE IV I melted together a glass which had a composition of r58.7%lead oxide, 36.6% germania, 4.2% lanthana and 0.5% Li20. The glass hadsimilar good transmission characteristics. The addition of the smallamounts of lithia used showed little eect on the infrared transmission;however, its presence reduced the index of refraction to someextenitt-hu's reducing reflection losses slightly.

I melted together 78.0% PbO, 18.0% GeOe, 4.0%` A1203. These componentsWere fusedL and allowed to solidify. Glass was obtained which had about'35.0% transmission at 6 microns.

7 EXAMPLE vr I melted together 75.0% lead oxide, 20.0% germania and 2%lanthana and 3% alumnia. Glass was obtained which transmitted about 30%of the rays, at a wave length of 6 microns.

EXAMPLE VII I melted together and fused a mixture of 70.0% lead oxide,29.0% germania, 1% zirconia and allowed the melt to solidify to form aglass which transmitted about of the rays at a wave length of 6 microns.

EXAMPLE VIII I melted together a glass which had a composition of 77.0%lead oxide, 18.0% germania, 4% alumina, and 1% zirconia. The glasstransmitted about oi the rays at 6 microns.

It is to be understood that the above described embodiments of myinvention are for the purpose of illustration only and various changesmay be made therein without departing from the spirit and scope of myinvention.

I claim:

1. A glass consisting of a plurality of oxides of which lead oxide andgermanium oxide comprise by weight at least 87% of the glass and ofwhich the remainder consists of lanthana and in which the glass consistsby weight of from a trace to 72% lead oxide, from 28% to 99.9% germaniaand from a trace to 13% of lanthana.

2. A glass consisting by weight of a trace to 72% lead oxide, from 28%to 99.9% germania and from a trace to 13% lanthana.

3. A glass consisting by weight of a trace to 79% lead oxide, from 17%to 99.9% of germania and from a trace to 11.5% alumina.

4. A glass consisting of a plurality of oxides of which lead oxide andgermanium oxide comprise by weight at least 87.0% of the composition ofwhich the remainder is lanthana, in which the ratio by weight of leadoxide to germania is at least as great as the ratio of' 0.01 to 1 and isnot greater than the ratio of 2.6 to 1 and in which the percentage byweight of lanthana is less than 13% of the composition.

5. A glass consisting of a plurality of oxides of which lead oxide andgermanium oxide comprise by weight at least 90.0% of the glass of whichthe remainder is lanthana, and in which the glass consists of from to72% lead oxide, from 28 to 45% germania and from a trace to 10%lanthana.

6. A glass consisting of lead oxide, germania, and lanthana in which theglass consists by weight of from 20 to 72% lead oxide, from 28 to 80%germania and from a trace to 13% lanthana.

7. A glass consisting by weight oi from a trace to 72% lead oxide, from28 to 99.99% germania and from a trace to 13% lanthana.

9. A method of making a glass consisting of lead oxide, germania, andnot more than 13% of a stabilizing component, said stabilizing componentcomprising an oxide selected from the group consisting of oxides ofaluminum and lanthanum, wherein the oxide of aluminum, if selected, isnot more than 11.5% and the oxide of lanthanum, il selected, is not morethan 13% which method consists of melting together components which aresilica free, of which lead oxide and germania comprise by weight atleast 87% of the mixture, and of which germania comprises by weight atleast 17% of the mixture in a container free from silica and thereaftermaintaining the glass in an atmosphere free or water,

while the glass is in a heated condition and during the cooling process.l

9. A method of making a glass consisting of lead oxide, germania, andnot more than 13% of a stabilizing component, said stabilizing componentcomprising an oxide selected from the group consisting of oxides ofaluminum and lanthanum, wherein the oxide of aluminum, if selected, isnot more than 11.5% and the oxide of lanthanum, if selected, is not morethan 13% which method consists of melting together components which aresilica free, of which lead oxide and germania comprise by weight atleast 87% of the mixture, in a container free from silica.

l-0. A method of making a glass consisting of lead oxide, germania, andnot more than 13% of a stabilizing component, said stabilizing componentcomprising an oxide selected from the group consisting of oxides ofaluminum and lanthanum, wherein the oxide of aluminum, if selected, isnot more than 11.5% and the oxide of lanthanum, if selected, is not morethan 13% which method consists of melting together the components ofwhich lead oxide and germania comprise by Weight at least 87% of themixture and of which germania comprises by weight at least 17% of themixture, removing the melt to and maintaining it until cooled in a gastight furnace and in an atmosphere free of water and water vapor, andpassing through the furnace a continuous stream of dry gas under aslight positive pressure.

l1. A method oi making a glass consisting of lead oxide, germania andnot more than 13% of a stabilizing component, said stabilizing componentcomprising an oxide selected from the group consisting of oxides ofaluminum and lanthanum, wherein the oxide of aluminum, if selected, isnot more than 11.5% and the oxide of lanthanum, if selected, is not morethan 13% which method consists of melting together the components ofwhich lead oxide and germania comprise by weight at least 87% of themixture and of which germania comprises by Weight at least 17% of themixture to form a glass, and removing the glass, and remelting the glassand maintaining it until cooled in a gas tight furnace and in anatmosphere free of water and water vapor.

12. A method of making a glass consisting of lead oxide, germania andnot more than 13% of a stabilizing component, said stabilizing componentcomprising an oxide selected from the group consisting of oxides ofaluminum and lanthanum, wherein the oxide of aluminum, if selected, isnot more than 11.5% and the oxide of lanthanum, if selected, is not morethan 13% which method consists oi melting together the components ofwhich lead oxide and germania comprise by weight at least 87% of themixture and or" which germania comprises by weight at least 17% of themixture and thereafter removing the melt to and maintaining it in anatmosphere free of water and water vapor, while the glass is in a heatedcondition and during the cooling process.

13. A glass consisting of a plurality oi at least three differentoxides, oi which lead oxide and germanium oxide comprise by weight atleast 37% of the glass; in which glass there is from a trace to 79% orlead oxide, from 17% to 99.9% of germania and at least a trace of athird oxide; and in which glass the remainder or the composition inaddition to the lead oxide and germanium oxide comprises an oxidepermitting the 9 use of a higher lead-germania ratio and being selectedfrom the group consisting of oxides of aluminum and lanthanum, whereinthe oxide of aluminum, if selected, is not more than 11.5% and the oxideof lanthanum, if selected is not more than 13%.

14. A glass of claim 13 in which said remainder consists of alumina.

15. A glass of claim 13 in which said remainder consists of lanthana.

16. A glass of claim 13 in which said remainder consists of a mixture ofthe oxides of manganese and lanthanum.

17. A glass of claim 13 in which said remainder consists of a mixture ofthe oxides of aluminum and zirconium.

18. A glass of claim 13 in which said remainder consists of oxides oflithium and lanthanum.

19. A glass according to claim 13 in which said remainder consistssubstantially of oxides of aluminum and lanthanum.

Name Date Dennis Nov. 23, 1926 Number

13. A GLASS CONSISTING OF A PLURALITY OF AT LEAST THREE DIFFERENTOXIDES, OF WHICH LEAD OXIDE AND GERMANIUM OXIDE COMPRISE BY WEIGHT ATLEAST 87% OF THE GLASS; IN WHICH GLASS THERE IS FROM A TRACE TO 97% OFLEAD OXIDE, FROM 17% TO 99.9% OF GERMANIUM AND AT LEAST A TRACE OF ATHRID OXIDE; AND IN WHICH GLASS THE REMAINDER OF THE COMPOSITION INADDITION TO THE LEAD OXIDE AND GERMANIUM OXIDE COMPRISES AN OXIDEPERMITTING THE USE OF A HIGHER LEAD-GERMANIA RATIO AND BEING SELECTEDFROM THE GROUP CONSISTING OF OXIDES OF ALUMINM AND LANTHANUM, WHEREINTHE OXIDE OF ALUMINUM, IF SELECTED, IS NOT MORE THAN 11.5% AND THE OXIDEOF LANTHANUM, IF SELECTED IS NOT MORE THAN 13%.